The present invention relates to a printing blanket construction, and more particularly, to a printing blanket including a reinforcing fabric ply comprised of a weft insertion fabric or a heavy gauge fabric, which reinforcing fabric ply provides all necessary tensioning properties to the blanket.
One of the most common commercial printing processes is offset lithography. In this printing process, ink is offset from a printing plate to a rubber-surfaced printing blanket mounted on a blanket cylinder before being transferred to a substrate, such as paper. Typically, the printing blanket is reinforced with a number of fabric plies to provide the desired low stretch and high tensile strength properties to the finished blanket. The fabric plies are typically comprised of woven blends of cotton and polyester or rayon ranging in gauge from 0.008 inches to 0.016 inches. They are typically stretched and finished such that the residual stretch is reduced. However, this is a cost additive operation as the fabrics must be treated in a separate procedure before being incorporated into the blanket construction. Often, two or more fabric layers are required in the printing blanket construction to achieve the desired low stretch and high tensile strength properties of the finished blanket. The multiple fabric layers also function to add thickness in order to achieve the desired gauge for the printing blanket. However, the fabrics typically used in the blanket construction are susceptible to gauge loss during printing operations, such that printing blankets which contain a number of fabric plies are more susceptible to gauge loss.
The addition of multiple fabric layers also adds to the complexity and cost of producing the printing blanket. It would be desirable to be able to provide a blanket construction having the desired tensioning properties, including low stretch and high tensile strength, which does not require the use of multiple fabric plies.
Accordingly, there is still a need in the art for a printing blanket construction which is low in cost to produce, which does not require the use of multiple reinforcing fabric plies, and which exhibits desirable tensioning and gauge retention properties.